Hello App: HelloCache.py

Contents

HelloCache.py

# cache.py - manage a cache of HelloApp data structures

# Written by Anthony V. Edwards

# 820 Churchill Drive, Chapel Hill, NC 27517

# ave@hanoversoft.net

# This file is the source (read-write) for these structures:

# HelloApp

# data structure caches

from Cache import Cache

import HelloApp

User_CACHE_MAX= 1000

# Used in mgmtHello.py, queryable by supervisor daemon

CacheList= "User" # the list of parameter categories

HelloCache_max= User_CACHE_MAX # the maximum size of the session cache

# The cache with all the instances

global cache

cache= None

def cacheAlloc(appname: str) -> bool:

Allocate our cache of HelloApp instances.

Specify how to manage the cache.

@param appname - the app name to use when querying system properties (ignored)

@return True upon success, False if any error encounted

# initialize the cache sizes

HelloCache_max= User_CACHE_MAX #Property::getValueInt(appname, "cache", "Hello", User_CACHE_MAX);

# Setup the cache

global cache

cache= Cache(HelloApp.HelloApp)

# specify how this cache should behave

cache.setReadOnly() # Don't auto-save anything

cache.setFetchDirect() # If it did fetch anything, fetch it directly from the data store (don't call HelloApp::cache())

cache.setSize(HelloCache_max) # Set the maximum size of the cache (when size exceeded, old instances would be save()ed before deletion)

# success

return True

def findPos(user_id: int) -> int:

global cache

return cache.findPos(user_id)

def add(user_id, session_object) -> bool:

global cache

return cache.add(user_id, session_object)

global cache

Get the instance in the cache at the position provided

@param pos - the cache position (as returned by findPos()) of the requested object

@return the object requested

return cache.cache[pos]['data']